Active drug entities are frequently derived from biological cultures including human and animal cells, bacteria, yeast, plant cells, hybridomas and any such biological compositions that are capable of replicating and undergoing metabolism. Additionally, biological entities are grown into organs and products of cell and gene therapy. The biological entities are routinely grown using traditional bioreactors and more recently disposable bioreactors.
Bioreactors are devices that convert nutritional elements into useful products using biological catalysts (biological culture) such as human and animal tissue cells, microorganism, baculoviruses and insect cells, etc. The main function of a bioreactor is to provide a controlled environment for the growth of the biological catalysts to obtain a desired product. A large number of designs of bioreactors are available as evidence by hundreds of patents issued to specific design elements of bioreactors. A variety of vessels and methods have been developed over the years to carry out chemical, biochemical and/or biological processing.
Although bioreactor systems and related processes are well known, improvements to such systems and processes would be useful in the preparation of a variety of products produced from a biological source. One such improvement is the environment where a bioreactor is operated. In the manufacturing of drugs and vaccines, an ISO 14644 Class 8 or Class Area classification of not more than 100,000 particles of 0.5 um per square foot is required. To maintain this air quality, the air is continuously passed through a HEPA filter and about 20 air exchanges per hour are required. To maintain this air quality standard, the HVAC systems, the HEPA filters and continuous air cleaning required adds to substantial capital and energy cost, often making it impossible for small companies or research organizations to produce drugs and vaccine for use in humans. Taking an example of a manufacturing facility requiring an airflow of 1 million cubic meters per hour, operating 24 hours a day for the whole year, and at a utility rate of $0.135 kW/h (Bureau of Labor Statistics, US Government for August 2011), the cost of operating the fans alone will be over half a million dollars. Other significant cost is the HEPA filters that must be replaced periodically, adding another half a million dollars to the total cost. The capital cost of an HVAC system is also very high; approximately $200 per square foot is added for the HVAC systems. In a 100,000 square foot facility, this adds about $20 Million to the cost of a project. While these costs are of lesser significance to large pharmaceutical and biotechnology companies, these form the key barrier to the development of drugs by smaller companies and research institutions, not able to afford these costs.
There are also instances, where a drug or vaccine may need to be manufactured in an emergency and in those instances the requirement of clean room environment impedes development and manufacturing.
There is a dire unmet need to create a bioreactor system that could be operated in a reasonably clean environment without the need for expensive HVAC systems. The atmosphere has about 2.5 million particles per square foot and the room air has about 1 million particles of size 0.5 um or larger. The room air is classified as ISO 14644 Class 9 or Level 1 according to the cGMP guidelines provided by the World Health Organization; it is also labeled as uncontrolled area classification. Reasons for requiring a controlled environment include protecting the product from environment and also protecting the personnel from the product; HVAC systems also prevent cross-contamination and are generally regarded as one of the most significant steps in assuring safety of the manufactured drugs.
To allow a bioreactor to operate in ISO 14644 Class 9 environment, it must have key features that will completely seal the bioreactor from environment for every step of the operation of a bioreactor. Once this can be validated and thus assured that there cannot be any contact between the environment and the contents of a bioreactor, it will be possible to operate these bioreactors in ISO 14644 Class 9 environment. However, bioreactors require supply of nutrition that includes oxygen and carbon dioxide and maintaining a flow inside a bioreactor without contaminating with the environment is a challenge that has not been met satisfactorily.
Prior art points to the system offered by Xcellerex (http://www.xcellerex.com/flexfactory-design.htm) that proposes to use proprietary FlexFactory process train that is comprised of disposables-based unit operations which minimizes the risk of cross-contamination. Each unit operation is enclosed in a controlled environment module (CEM), which is co-located in common, controlled manufacturing space. The CEM provides a localized clean environment around the equipment and with positive pressure to the room. The environmental standards for the FlexFactory CEM's are based on traditional clean room standards. Operators stand outside the CEM and access the equipment access through iris ports. The need for multiple airlocks and gowning and re-gowning rooms is eliminated. While this system provides isolation of operation, the plan is flawed because there is no definite way to assure that a breach in the system will not take place and if it does, then it will immediately contaminate the product. This concept has some applications but it is unlikely that the regulatory agencies would allow use of the FlexFactory for commercial production of biological drugs.
The present invention provided a completely closed bioreactor wherein all inlets are provided through a 0.22-micron filter, the exhaust recirculates and the nutrient medium outlet is kept sealed until the bioreactor is ready for draining. Additionally, all those contacts where a clean room exposure is required such as introduction of biological culture and handling the manufactured product are conducted in controlled environment.
The present invention of a closed bioreactor can be operated without the limitations of the FlexFactory of a physical space where it must be located, it can be of any size, a limitation of FlexFactory, and provides continuous protection of the product from the environment and the environment from the product. The major difference between the FlexFactory and the present invention is that the present invention protects the product directly, while FlexFactory provide a protection around the container holding a product.
The present invention also reports a single-use or disposable bioreactor. The traditional drawbacks in the design of bioreactors have led to the development of disposable bioreactors. During the past ten years, there has been a significant move towards using disposable or single-use bioreactors (SUB) to avoid cross-contamination and reduce the cost of validation (cleaning) between batches; the risk of viral contamination has further hastened the development of these single-use bioreactors. The design of single-use bioreactor can mimic the stirred tank as disposable liners with embedded or magnetically driven stirrers are used while the rocking motion type bioreactors are used without internal stirring. Despite significant development in this field, the utilization of these types of bioreactors has not been very successful for cells or organisms requiring high rates of oxygenation since that would require strong stirring that is not readily possible with disposable systems. Examples of SUBs are systems based on wave agitation. See, e.g., U.S. Pat. No. 6,544,788; PCT Publication WO 00/66706. This type of bioreactor may be used to culture relatively sensitive cells such as CHO cells (e.g., Pierce, Bioprocessing J. 3: 51-56 (2004)), hybridoma cells (e.g., Ling et al., Biotech. Prog., 19: 158-162 (2003)), insect cells (e.g., Weber et al., Cytotech. 38: 77-85 (2002)) and anchorage-dependent cells (e.g., Singh, Cytotech. 30: 149-158 (1999)) in a single disposable container. Such disposable units are relatively cheap, decrease the risk of infection because of their single use and require no internal stirring parts to facilitate gas exchange. More common techniques for mixing the nutrient media include rocking, shaking, vibrating, compressing the walls of the container and in bubble reactors, using gas to stir the liquid.